Concentration of minerals



Patented Feb. 20, 1923. i I

UNITED STATES PATENT OFFICE;

WALTER O. BORCHERDT, OF AUSTIN VILLE, VIRGINIA, ASSIGNOR TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

Application filed March 19, 1919, Serial No.'283,629. Renewed May 19, 1922; Serial No. 562 266.

To all whom itmag concern.

Be it known that I, WALT R O. BOR- and other suspended matters and heavily -cHERnT,a citizen of the United States, residcharged. with both organic and inorganic ing at Austin-ville, in the county of Wythe, colloids, run into the source from which 5 State of Virginia, have invented certain new the milling wateris customarily taken.

and useful Improvements in the Concentra- The colloidal matters may be present. as tion of Minerals; and I do hereby declare pure colloids, organic or inorganic, or in the following to be a full, clear, and exact a state bordering on the so-called coarse description of the invention, such as will suspensions. Throu hout this specificalo enable others skilled in the art to which it tion and th append appertains to make and use the same. to embrace in the expressions colloids and 's invention relates to the concentra- (or) colloidal slimes and colloidal constition of ores by flotation. tuents both true colloids and those quasi I It is well known that colloids and colloior borderland substances, which ma not dal slimes, both organic and inorganic, often be truly colloidal but partake o the are present in mineral ore pulp, and when qualities of, or resemble, colloids, and withof such ore pulp by flotation. IVhen conpurposes of the present invention, the colloi- 20 siderable amounts of colloids or colloidal dal constituents may be considered as rangslimes are thus present it is usually necesing from just above the molecular size upsary to operate in a more dilute pulp; or ward through the class of so-called suspenthe froth produced is rendered thick, vissolds, which, while possibly not true col- 0011s and difiicult to break down or reliqlo-ids, still, because of their relatively large 25 uefy and to handle in launders, pumps and specific surface, exhibit some, if not all, pipes, in which condition it is spoken of as of the propertiesof colloids, and are capabeing over stabilized, because of its conble of existing in both the sol or gel state, tent of colloils or colloidal slimes, and or of being dispersed andcoagulated, or gives a dirty concentrate.

30 It has been proposed to treat such Lore dal sllme, therefore, I mean a material' pulps, containing considerable amounts of Which is not necessarily a true colloid, but

' colloidal slimes, with a coagulating or flocexhibits colloidal characteristics to a sufliculating agent, in order to neutralize in Cient degree to make it amenable to the part the ob ectionable effect of such slimes'; manipulation hereinafter described.

35 but the coagulated or flocculated constitus the result of my investigations, I beents remain admixed with the ore pulp and lieve that the injurious action on the flotaoften seem to form therewith adsorption tion operation of colloidal matters presentoo compounds or colloidal complexes whereiii/{the ore pulp may result merely from 'with the mineral particles are entangled or their presence in, the ore pulp, or may be 40 enmeshed and the flotation operation prejudue to their attachment to, or adsorption diced thereby, as well as, in some instances by, the flotation agent, or the gaseous flotaby the coagulating or flocculating agents tion medium, or the mineral particles, 01 which remaln in solution in the -ore pulp. all three. It is my belief that these colloi- The colloidal matters present in an orc dal matters interfere-*wvith the flotation 45 pulp are probably derived for the most part operation whether theyexist in a flocculated I from the gangue particles of the ore, al- (or coagulated) or in a deflocculated (or though it is not unlikely that mineral artidispersed) condition, but I have found that cles may also be present in the pulp in the in general their action is less marked when form of colloids. Such colloidal matters dispersed or deflocculate'd.

50 may also beintroduced with the milling I have discovered that the concentration water which isused to form the ore pulp, by flotation of the mineral particles of an and this source of colloidal matters may-be ore pulp is often very considerably aided considerable during periods of heavy rainand improved by removing the flotation-invaluable minerals as it may .ot the colloids or hibitory colloidal constituents, in whole or in part, from the pulp prior to the flotation operation proper, and in my copendlng application, Ser. No. 283,628, filed Mar 19, 1919 one aspect of this improvement 1n the method of concentrating minerals by flotation is described and claimed. In the aforementioned application I have particularly described the removal of the colloidal constituents from the ore pulp by dispersing or deflocculating-them and bringing about the sedimentation of the mineral particles and separating the dispersed or deflocculated colloidal constituents by decantation. The

resent invention involves the removal of the flotation-inhibitory colloidal constituents from the ore pulp by a flotation treatment under conditions permitting the removal by flotation of a part or the whole of the colloidal constituents while substantially inhibiting the flotation of mineral particles. I

According to the present invention, the ore pulp containing the colloids or colloidal slimes is subjected to a preliminary flotation treatment with an appropriate agent or agents. the object of which is to produce a froth or scum containing part or the whole colloidal slimes, with a relatively small proportion of the valuable mineral or minerals contained in the pulp, and to seperate this colloid-bearing troth from the bulk' of the ore pulp. after which the ore pulp is treated by flotation tor the recovery of its valuable constituents by any desired flotation process and agents.

The colloid-bearing froth may itseli be further treated for the recovery of such contain, or it may be run to waste. but in either event the principal part of the mineral contained in the ore-pulp is by this process treated under conditions which tacillitate and enhance the recovery of such mineral and permit of the flotation being conducted upon a more thickened pulp than would otherwise be the case. thereby increasing the effective capacity oi the flotation plant. pumps. settling tanks. filters. etc.. used in connection with it. by decreasing the bulk of pulp to be handled for a given tonnage of dry ore.

In some casesthe colloid-bearing iroth when produced as described may contain too much valuable mineral to permit of throwing it away. This mineral may be carried over in part mechanically entangled with i'loccllles of colloidal material: in part ascolloidal complexes or mineral. particles with adsorbed colloid coating which cause them to act like gangi'ie or colloidal particles rather than mineral particles: and in part simply in mechanical suspension in the froth. because ot'their tine size and the rapid formation of the froth. In order to separate this mineral from the colloid-bearther treated in a similar manner,

IAMLQQQ V froth and return it to the pulp whiching been treated as described for the rehas moval of colloidal material, the froth may be subjected to the action of water or air jets to break it down, as is commonly done in froth-flotation plants, and it the froth contains flocculent material, as would ordinarily be the case, a deflocculating agent may be added as well as water for dilution of the broken down froth-pulp to the desired degree. The kind and amount of deflocculating agent, and the amount of water required may be readily determined for a specified colloid-bearing froth by means of simple tests.

- The deflocculated pulp resulting from the foregoing-described treatment may be then run to settling tanks, which may be of the continuous type, such as Dorr, Allen'or Callow, tanks or similar apparatus. or intermittent tanks, such as are commonly used ,in the arts and are too well known to require description. In these tanks sedimentation or settling may take place, the minerals and coarse gangue particles settling toward the bottom. and being removed continuously or intermittently and the deflocculated colloidal material. together with much of the agent used to form the colloid-bearing froth. having a much slower settling rate, remains in suspension and is continuously or intermittently overflowed to waste. The settled material. containing the mineral. may be furif the first treatment has not sufliciently removed the colloidal material and the froth-forming agent and may be then diluted with water as desired and returned to the body of the pulp'which has been treated for the removal of colloids. or be otherwise disposed oi in any other manner.

In some cases, simple breaking down of the colloid-bearing froth and dilution with water may be sufficient to render possible the separation of the colloidal constituents from ill) the mineral particles and the return of the iect varies in strength as respects different 1 and also. as respects any one minerals: mineral. that the inhibitory efiect varies approximately in proportion to theamount oi colloidal material present: and that the state.

in which the colloids exist also has a bearing. 1

' of each of the valuable minerals in the origi.;

proper application of sible to secure the differential or preferential flotation of certain mineral or minerals while inhibiting the flotation of another or other minerals, and according to the present invention this result is brought about by forming a colloidbearing froth by means ofa suitable agent,

these facts it is posprocesses, such as Callow, J anney, K and K, etc., but preferably the Callow or other pneumatic machines, (since in these th it to further treatment. separate from the ore pulp. After sufficient of the colloidal c011- stituents have been removed the pulp is treated by flotation in the example, in the flotation machines commonly used quires, for the production and remoyal of a mineral froth, composed principally of one of the valuable minerals. The tailings pulp from this operation isthen again treated with suitable agents in a suitable flotation machine for the production of a second colloid-bearing froth, which is also removed and discarded, or retreated. as may be desired; and the remaining pulp is then subtime to a flotation treatment for the recovery of a concentrate composed principally of a second valuable mineral this sequence of operations being repeated as ual ore pulp. singly or in groups.

As an example of the application of the process of the present invention I will describe the treatment of an ore like that found at Austinv'ille. Va. which contains the sulphides of lead. zinc and llOIl 1n dol-' omitic limestone and in which the colloids or colloidal slimes are present in such quantit v as to seriously interfere with the recovery of the valuable minerals b the usual flotation processes. To the finely ground ore, which has been made by admixture with water, is added a small action is more readily usual way, for

into an ore pulp.

amount, for example, one-half pound per 1 ton of dry ore, of a rosin soap in solution in water. After thorough mixture the is passed into aCallow flotation cell, the porous bottom of sure is admitted in fine streams to form minute air bubbles. These air with the rosin soap and the colloidal constituents of the bearing froth which rlses to the surface of the pulp in the cell and overflows into an After suflicient of the colloidal constituents have thus been removed the ore pulp is passed to 'another flotation cell where a mineral floating agent, as for expound per ton of dry ore, in solution in water, and passed into another flotation cell where a second colloid-bearing froth is formed and removed as before. The ore passed to another flotation cell and a small amount of pine oil and crude petroleum oil in emulsion are added and a flotation operation conducted for the V a blende froth, which is removed and further treated as is customary. To the ore pulp, is then added a further small amount of rosin soap, for example one-quarter pound per ton of dry ore, in solution in water, and the ore pulp is then passed into another flotation cell where the remainder of the colloidal constituents of the ore are removed in the form of a colloidbearing frothas'before. The ore pulp is then mixed with a small quantity of sulphuric acid. for example oneehalf pound per ton of dry ore, and with emulsified pine oil and crude petroleum oil and passed into a flotation cell where ,a mineral froth containing the pvriteis formed and. removed. while the final tailings pulp from the cell According to the present invention, the yolloidal constituents of tlie- .ore pulp which are td lie removed in whole or in part by the formation of a colloid-bearing froth, may be in either a flocculat'ed or deflocculated condition. the preference being determined by economic considerii'tions depending upon the kind minerals contained in the ore. the amount of colloidal matter present. the average tineness of the valuable minerals. the tendency or otherwise of the flocculated colloids to enmesh or entangle valuable mineral. the soluble contaminantsof the ore pulp. the degree of dilution of the ore pulp, the subof valuable mineral or sequent treatment to which the colloid-bearof factors, some of ing froth and ore pulp or mineral concentrate, respectively, ma be subjected, the tonnage to be treated, t e cost of water and agents, etc. In any actual casethe natural character of the ore and other fixed conditions will determine certain features of the exact method of treatment, while the preference as to other features may be readily determined by simple tests which will in'each case be suggested by the problem itself.

In the production of colloid-bearing froths, many agents or combinations of agents are available. .One at least of the agents must be such as will be capable with air or gas bubbles in the pulp or forming a froth o1 scum which will rise to the sur face of the pulp. In the investigation of this discovery I have found many agents, both organic and inorganic which are effective, but thier relative value in the case of. any" given ore will depend upon a variety which are mentioned above, and simple tests will in any event determine the most suitable agent or agents. I have found in practice that pine and hardwood tar oils, rosin oils, or in general oils with a high pitch content, make excellent agents for the formation of colloid-bearing froths, substantially non-selective for the valuable minerals present in the ore pulp. Soaps of various kinds, and especially rosin soaps, are excellent with some ores, and generally give abundant froths. In many cases for the production a given ore will yield an excellent colloidbearing, substantially non-mineral selective froth for the purpose of the present invention, if simply used in excess over what would be practicable for the formation of a mineral-bearing froth. In such .cases as the last a very simple operation may result, as it is well known that, when a frothing agent is added to water and a froth is produced, that the greater part of the frothing agent concentrates in the froth, and is consequently eliminated with it from the pulp, from which it results that after the colloidal constituents of a pulp have been removed by'means of a colloid-bearing froth, that the remaining frothing agent in the orepul-p may be suflicient for the production of a mineral froth according to the usual processes.

In such cases as it is necessary to use for the formation of the colloid-bearing froth an agent or agents whose residual presence in the ore would be objectionable in the subsequent mineral flotation, it is possible to neutralize such residual portions-by commonly understood chemical means, an have found, as a result of my investigations, that when an ore pulp has been approxid subjecting the mineral pulp incense mately freed of its colloidal that mineral flotation can be conducted satisfactorily in the resence-of much larger quantities of solub e impurities than would otherwise be practicable.

The present invention is applicable to different flotation processes and with various means or reagents or agents which are used to effect or facilitate flotation. Thus, while the invention has herein been more particularly described in connection with froth flotation, it is to be understood that the invention is equally advantageous in connection with surface film flotation processes, as in connection with other processes ing' the principles of flotation I claim:

involvas well- 1. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises separating the colloidal constituents from the mineral pulp by a preliminary frothflotation treatment, and thereafter subjecting the pulp to a flotation operation.

2. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises subjecting the mineral pulp to a preferential froth-flotation treatment by which the colloidal constituents are removed to a desired extent from the pulp, and thereafter subjecting the pulp to a flotation operation;

3. The method of improving the flotation of minerals associated in a mineralpulp with colloidal constituents, which comprises to a preliminary froth-flotation treatment under conditions permitting the icmo-val by flotation of the colloidal constituents while substantially inhibiting the flotation of mineral particles, and thereafter subjecting the pulp toa flotation operation.

4. The method of improving the flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises subjecting the mineral pulp to apreferential froth-flotation treatment by which the colloidal constituents are remov d to a desired extent'from the pulp, thereafter subjecting the pulp to a flotation operation, and subjecting the removed colloid-bearing froth to further treatment for the separation therefrom of mineral particles carried thereby.

5. The method of effecting the selective flotation of minerals associated in a mineral pulp with colloidal constituents, which comprises subjecting the mineral pulp to a preferential froth-flotation. treatment by which the colloidal constituents are removed to a desired extent from the pulp to permit flotation of a certain mineral constituent thereof while substantially inhibiting the flota- I tion of other mineral constituents thereof,

preferential froth-flotation treatment for efsubjecting the mineral pulp to a froth flotafecting a further removal of the colloidal tion treatment under conditions producing constituents to permit the flotation of a fura colloid-bearing froth, removing such froth ther mineral constituent of the ore pulp,and from the mineral pulp to an extent suf- 8 subjecting the ore pulp to a flotation opera ficient to reduce the flotation-inhibitory eftion for effecting the removal therefrom of fects of the colloids therein, and thereafter said further mineral constituent. subjecting the remainin 6. The method of improving the flotation flotation operation. of minerals associated in a mineral pulp In testimony whereof I affix my signature. 10 with colloidal constituents, which comprises lVALTER O. BORCHERDT. 

